Black Holes Go 'Mano a Mano' (NASA, Chandra, 10/06/09)

This image of NGC 6240 contains new X-ray data from Chandra (shown in
red, orange, and yellow) that has been combined with an optical image
from the Hubble Space Telescope originally released in 2008. In 2002,
the discovery of two merging black holes was announced based on
Chandra data in this galaxy. The two black holes are a mere 3,000
light years apart and are seen as the bright point-like sources in the
middle of the image.

Scientists think these black holes are in such close proximity because
they are in the midst of spiraling toward each other -- a process that
began about 30 million years ago. It is estimated that the two black
holes will eventually drift together and merge into a larger black
hole some tens or hundreds of millions of years from now.

Finding and studying merging black holes has become a very active
field of research in astrophysics. Since 2002, there has been intense
interest in follow-up observations of NGC 6240 by Chandra and other
telescopes, as well as a search for similar systems. Understanding
what happens when these exotic objects interact with one another
remains an intriguing question for scientists.

The formation of multiple systems of supermassive black holes should
be common in the Universe, since many galaxies undergo collisions and
mergers with other galaxies, most of which contain supermassive black
holes. It is thought that pairs of massive black holes can explain
some of the unusual behavior seen by rapidly growing supermassive
black holes, such as the distortion and bending seen in the powerful
jets they produce. Also, pairs of massive black holes in the process
of merging are expected to be the most powerful sources of
gravitational waves in the Universe.